The present disclosure discloses a FinFET transistor cut etching process method, comprising: step 1, forming a first photoresist pattern to define a cut etching region of the FinFET transistor; step 2, forming a second amorphous semiconductor pattern; step 3, forming a first dielectric layer and a first groove; step 4, forming a second dielectric layer that fully fills the first groove; step 5, performing CMP using the second amorphous semiconductor layer as a stop layer, so as to form a sidewall and a second dielectric layer strip; step 6, performing self-alignment to remove each side wall; step 7, performing a wet process to remove the amorphous semiconductor strip; and step 8: performing etching by using each second dielectric layer strip as a mask, so as to form a fin and achieve cut etching of the FinFET transistor. The present disclosure can enlarge the process window and reduce the process cost.